If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Intel HD 4000 and three monitors

02-25-2013, 11:22 PM

I read here that "3 monitors are support by Ivybridge only if 2 of those are identical and running at the same resolution (such as DP+DP, HDMI+HDMI etc)." I also read at Phoronix that "This means that two of the three outputs need to have the same connection type and same timings. However, most people in a triple monitor environment will have at least two -- if not all three -- of the monitors be identical and configured the same, so this shouldn't be a terribly huge issue." I have also seen this graphic (which I think might have come from Intel originally) suggesting that only systems with dual DisplayPorts can use three monitors (which is also repeated in the Intel FAQ).

So my question is - has anybody actually got three identical monitors running off the integrated graphics with, say, HDMI+HDMI+DVI? I can't find any reports where someone says they did it and it worked. Are there any mITX motherboards which support this? Or have dual DisplayPort?

The only SFF system I could find that should work is the Dell 9010, which has dual DisplayPort and VGA (not ideal). I do have three identical monitors with DVI-D (same clock) so according to the freedesktop people it should work, I am just sceptical as I have not seen a single person who says "works for me".

Comment

It looks like you are running some version of Ubuntu 12.04? As far as I can see, the latest Intel driver in 12.04.02LTS was released in Feb 2012, which is pretty old. So you might want to try something more recent: either the Xorg Edgers PPA, Ubuntu 12.10 or the 13.04beta, or the Intel installer at https://01.org/linuxgraphics/

Comment

It looks like you are running some version of Ubuntu 12.04? As far as I can see, the latest Intel driver in 12.04.02LTS was released in Feb 2012, which is pretty old. So you might want to try something more recent: either the Xorg Edgers PPA, Ubuntu 12.10 or the 13.04beta, or the Intel installer at https://01.org/linuxgraphics/

You are correct. It is Ubuntu 12.04.2. Kernel and X version in 12.04.2 should be the ones from 12.10. I've tried Xorg Edgers PPA - no luck. Intel installer have issues with package names and fail to install on 12.04.2.

AFAICT looks like the problem resides in the kernel. I've tried with stock kernel 3.9 and thing are slightly better: It dose not hangs on boot (probably because resolution is automatically set to 1024x768 for all outputs). However raising resolution to monitor native values reproduce the error.

You've mentioned in previous posts that there are some resolution limitation - but exactly the same monitor configuration works fine in Win7 so I assume that hardware is ok.

Intel installer have issues with package names and fail to install on 12.04.2.

Ubuntu 12.04 is supposed to be supported by the Intel installer, so report it as a bug to Intel if it doesn't work. Make sure that you're on a fresh install though (if you've mixed 12.04 base with random PPA packages they will likely say it's unsupported)

Comment

It sounds like a bug. I would report it as a bug at https://01.org/linuxgraphics/community/kernel and ask on the intel-gfx mailing list.
I've had problems in the past with mismatched kernel/xorg versions so it's usually best to try the same versions as upstream are using for testing.

Ask on mailing list, report a bug. Got it. Thanks.

Ubuntu 12.04 is supposed to be supported by the Intel installer, so report it as a bug to Intel if it doesn't work. Make sure that you're on a fresh install though (if you've mixed 12.04 base with random PPA packages they will likely say it's unsupported)

ppa-purge usually take good care of removing PPA specific packages.

Yeah, Intel installer dose support 12.04 but it gets confused with 12.04.2 where some packages are named a bit different e.g. xserver-xorg-lts-quantal xserver-xorg-video-intel-lts-quantal ...

BTW, connecting all three monitors via HDMI works fine. And monitors with DVI inputs connected via HDMI adapters don't work on this board.
I've never encountered device that actually care if it is DVI or HDMI (This lead me to belief that same digital signal propagate no matter what connector type is (DVI, HDMI or DisplayPort))

BTW, connecting all three monitors via HDMI works fine. And monitors with DVI inputs connected via HDMI adapters don't work on this board.
I've never encountered device that actually care if it is DVI or HDMI (This lead me to belief that same digital signal propagate no matter what connector type is (DVI, HDMI or DisplayPort))

Are the monitors and cables DVI-D? DVI-I also carries an analog signal so it is possible for hardware to be DVI-I only.

Also for three identical (same pixel clock) monitors to work I have read that the connection type is also supposed to be the same - but I never understood if DVI-D and HDMI are considered "the same" in this context so you can mix them. http://en.wikipedia.org/wiki/Intel_H...ctive_displays

See also: Digital_Visual_Interface#Clock_and_data_relationsh ip

Ivy Bridge HD2500 and HD4000 chipsets are advertised as supporting three active monitors but many users have found that this does not work for them due to the chipset only supporting two active monitors in many common configurations. The reason for this is that the chipset only includes two PLLs; a PLL generates a pixel clock at a certain frequency which is used to sync the timings of data being transferred between the GPU and displays. Therefore, three simultaneously active monitors can only be achieved by a hardware configuration that requires only two unique pixel clocks, such as:

* Using 2 or 3 active DisplayPort connections. DisplayPort requires only a single pixel clock for all active connections, regardless of how many there are (this is not the case for non-active connections, which would require an extra pixel clock for each connection)

* By using two non-DisplayPort connections of the same connection type (ie. HDMI+HDMI) and same clock frequency (ie. connected to two identical monitors at the same resolution) so that a single unique pixel clock can be shared between both connections.